class Solution {
public:
    bool lemonadeChange(vector<int>& bills) {
        int five = 0, ten = 0;
        for (auto bill : bills)
        {
            if (bill == 5)
                five++;
            else if (bill == 10)
            {
                if (five == 0)
                    return false;
                else
                {
                    five--;
                    ten++;
                }
            }
            else
            {
                if(five > 0 && ten > 0)
                {
                    five--;
                    ten--;
                }
                else if (five >= 3)
                    five -= 3;
                else
                    return false;
            }
        }

        return true;
    }
};